1. Technical Field
The present invention relates to a sheet folding apparatus for folding a sheet with an image formed thereon, and more particularly, to improve the transport mechanism for selectively performing folding processing on a sheet in a transport path for carrying the sheet from a carry-in portion to a carrying-out portion.
2. Description of the Related Art
Generally, this type of sheet folding apparatus has been known as an apparatus for folding a sheet with an image formed thereon by an image formation apparatus such as a printing press, printer apparatus and copier in a predetermined fold position to perform finish processing. For example, Japanese Patent Application Publication No. 2009-018494 proposes an apparatus which is coupled to a sheet discharge outlet of an image formation apparatus, folds a sheet with an image formed for filing, and carries the sheet out to subsequent binding processing.
The sheet folding apparatus for thus folding an image-formed sheet in half or one-third to carryout is configured as an independent apparatus as a post-processing apparatus of the image formation apparatus, or as a unit incorporated into the image formation apparatus or binding processing apparatus. Then, as a folding form, for example, for filing, various folding forms such as ½ folding, ⅓ Z-folding and ⅓ letter-folding are known corresponding to the intended use.
Then, the folding apparatus which is thus coupled to or incorporated into the image formation apparatus, binding apparatus (finisher apparatus, bookbinding apparatus) or the like requires a path (sheet discharge path) for carrying a sheet that is fed to a carry-in entrance (portion) out to a carrying-out exit (portion) without performing the folding processing on the sheet and another path (folding processing path) for carrying a sheet to the carrying-out exit after performing the folding processing on the sheet. Therefore, in Japanese Patent Application Publication No. 2009-018494, the sheet discharge path is provided between a carry-in entrance and carrying-out exit formed in an apparatus housing, the folding processing path is disposed below the sheet discharge path, a sheet without undergoing the folding processing is fed to the carrying-out exit from the sheet discharge path, and a sheet to undergo the folding processing is guided to the folding processing path and fed to the carrying-out exit after undergoing the folding processing.
Japanese Patent Gazette No. 4144496 discloses a sheet processing apparatus provided with a similar sheet discharge path and folding processing path. Then, in the folding processing path are disposed folding rollers for performing first folding on a sheet and folding rollers for performing second folding on the first-folded sheet, and the sheet from the carry-in entrance is folded in ½ or ⅓.